Sn as an etching mask?

jim kruger jimkruger at
Mon Jul 16 15:41:54 PDT 2012

Thanks for asking first.  

Sn is allowed, but it will not serve as a mask for CL2 etch.  Sn is rapidly etched in Cl2.
It is also very soft and sputters rapidly.

It is not likely to cause III-V issues since SnCl4 is volatile and will be pumped away (BP = 114C).
For even more caution, try to use it in Fluorine week, just before the wet clean.  

I think you will need a different mask material anyway.

Why Sn?

SiO2 or Cr would make good masks for Cl2.
What exactly is your requirement?


 From: Sangmoo Jeong <popomoo at>
To: pquest at 
Sent: Monday, July 16, 2012 2:20 PM
Subject: Sn as an etching mask?
Dear pquest users

I'd like to use the pquest machine with a thin-film of Sn.
The thickness of Sn would be 30~60 nm and I plan to use it as an etching mask for Si.
And, the gas etchant would be Cl2, but I have no idea about by-products after etching.

Mary was concerned about the doping effect to III-V materials by Sn.
If I can use Sn on this machine, I will plan to use it about once a week for less than 30 min.

I will definitely request SpecMat about the feasibility check of Sn for pquest,
but I want to check first whether any pquest users have problems with Sn.
Please let me know if you have opinions or concerns.


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